CN1838272A - Diffraction element and optical disk device - Google Patents
Diffraction element and optical disk device Download PDFInfo
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- CN1838272A CN1838272A CNA2006100681910A CN200610068191A CN1838272A CN 1838272 A CN1838272 A CN 1838272A CN A2006100681910 A CNA2006100681910 A CN A2006100681910A CN 200610068191 A CN200610068191 A CN 200610068191A CN 1838272 A CN1838272 A CN 1838272A
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- slot part
- diffraction element
- central area
- light
- petiolareas
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1861—Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1353—Diffractive elements, e.g. holograms or gratings
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- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
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- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
The present invention provides a diffraction element and an optical disk drive capable of improving the flexibility for setting the aperture and the optical magnification by making it possible to set the spot shape of the main beam and the diffraction efficiency as desired. In the optical disk drive 1, the diffraction element 8 for forming three beams has a high +-primary diffraction efficiency at the center area 86 in the length direction of the groove 81 and a low +-primary diffraction efficiency at both ends 87, 88. Accordingly, since the 0th light from the center area 86 loses its light intensity largely but the 0th light from both ends 87, 88 loses its light intensity less, the shape of the peak of the 0th light has raised skirts and an equivalent effect is obtained as increasing the NA. Thus, the main beam spot can be made small in diameter when focusing it on the optical recording disk 10. Further, since wasteful high order diffraction light is not generated, the sub-spot can be made large.
Description
Technical field
The optical disc apparatus that the present invention relates to alternately to arrange the diffraction element of slot part and convex strip portions and have this diffraction element.
Background technology
As optical recording being carried out information record or used again composition, various compositions have been proposed, but when adopting arbitrary composition, optical disc apparatus all has lasing light emitter, photodetector, formation the lasing light emitter emitting laser to be directed to the optical system of returning light path of going to light path and the return light may of optical recording reflection being directed to photodetector of optical recording basically.And, in optical disc apparatus, use various diffraction elements.
For example, disclosed technology is when utilizing DPP (differential recommending) etc. to obtain tracking error signal, produce the beamlet that main beam that 0 light forms and diffraction light are formed by diffraction element according to the light of lasing light emitter outgoing, and will in the zone long-pending, form the diffraction element of slot part as this diffraction element less than beam cross section, with the light beam of diffraction light and no diffraction, offset tracing deviation and (for example refer to Patent Document 1: the flat 10-162383 communique of Japan's patent disclosure).
A kind of diffraction element is proposed again, this element is a purpose with the spot size of fully dwindling on the CD, make groove width near half the length in grating cycle near the center, near half the length away from the grating cycle outer edge (for example refers to Patent Document 2: the patent disclosure 2004-295954 of Japan communique).
Yet under the situation of the diffraction element of patent documentation 1 record, the phase place of main beam is in the zone with slot part and do not form between the par of slot part and produce big difference.Thereby existence can not prevent to produce the problem that differs.
Under the situation of the diffraction element that patent documentation 2 is put down in writing, owing to change the grating duty factor, in duty factor departs from 50: 50 zone, the diffraction efficiency of 3 times, 5 times, 7 times high orders such as diffraction light uprises, when the result thinks to improve the laser utilization ratio a little at recording optical disc apparatus like that, there is the opposite problem of effect.
In view of the above problems, problem of the present invention is, thereby provides a kind of condition that light spot shape and diffraction efficiency can be set for hope can improve the diffraction element of NA degree of freedom and optics multiplying power degree of freedom and use the recording disk device of this element.
Summary of the invention
In order to solve above-mentioned problem, diffraction element of the present invention is alternately arranged many slot parts and convex strip portions, and wherein, the depth dimensions from the upper surface of both sides convex strip portions that described slot part is clipped in the middle to the bottom of this slot part is because of the position changes.
Use diffraction element of the present invention, can be used for optical recording is carried out the optical disc apparatus of recording of information, reproduction or these both usefulness.This optical disc apparatus has the optical system of returning light path of going to light path and the return light may of described optical recording reflection being directed to photodetector that lasing light emitter, photodetector, formation are directed to described lasing light emitter emitting laser optical recording, and described optical system produces described diffraction element and use element as 3 light beams, and this 3 light beam produces with element in described half-way of going to light path, form the main beam of 0 light composition and 2 beamlets of diffraction light composition according to the light of described lasing light emitter outgoing.
Use diffraction element of the present invention,, light spot shape and diffraction efficiency can be set for the condition of hope, can improve the degree of freedom and the optics multiplying power of aperture because the depth dimensions of slot part changes because of the position.For example, to use diffraction element of the present invention produces when being used for optical disc apparatus with element as 3 light beams, form the main beam of 0 light composition and the beamlet that diffraction light is formed according to the lasing light emitter emitting laser, the depth dimensions of the slot part of diffraction element then from the upper surface of both sides convex strip portions that this slot part is clipped in the middle to the bottom of this slot part, because of the position changes, so when the diffraction element with by preceding comparison, the peak shape of 0 light becomes the shape that the peak pin improves the share that partly is subjected to diffraction (for example central area reduce share).Therefore, 0 luminous energy that incides object lens is obtained the effect identical with strengthening NA, thereby when making main beam converge on the track of optical recording, can make spot diameter little.Like this, can set light spot shape and diffraction efficiency the condition of hope for, thereby can improve the degree of freedom of aperture and the degree of freedom of optics multiplying power.Owing to but the duty factor former state to diffraction element kept 50: 50, can suppress to produce the high order diffraction light again, and can amplify spot diameter the beamlet that converges on the optical recording track.Therefore, the positional precision tolerance of track and beamlet is widened, and improves operating efficiency in the time of can seeking to make CD.Even the optical recording that the track spacing is different also can suitably be obtained tracking error signal.
Among the present invention, the composition that can adopt described depth dimensions to change with step-wise manner at the length direction of described slot part, or described depth dimensions is formed at the length direction continually varying of described slot part.
Among the present invention, also can adopt the different composition of described depth dimensions between described many slot parts.
Among the present invention, the center of the depth direction of described slot part preferably is in highly identical position on this slot part length direction.Form like this, can prevent the astigmatism that diffraction element causes.
Among the present invention, the center of depth direction that can adopt described slot part is at the composition of the length direction height change of this slot part.
Among the present invention, the center of the depth direction of described slot part preferably is in position highly identical between each slot part.Form like this, can prevent the astigmatism that diffraction element causes.
Among the present invention, the center of depth direction that can adopt described slot part different composition between each slot part.
In the invention described above, preferably described many slot part and the convex strip portions alternately arranged forms respectively and has the central area big from the upper surface of described convex strip portions to the depth dimensions of the bottom of described slot part and described depth dimensions two petiolareas less than described central area, and will set for across described central area and described two petiolareas from the incidence zone of the laser of semiconductor laser.At this moment, preferably alternately arrange the width dimensions that many slot part and convex strip portions form described slot part and equate described respectively, and the duty factor of grating is 50: 50.
In the invention described above, the bottom that is lower than described two petiolareas can be formed on the bottom of the slot part of described central area, and the upper surface of the described convex strip portions of described central area is formed the upper surface of the described convex strip portions that is higher than described two petiolareas, little by the depth dimensions depth dimensions big, described two petiolareas simultaneously of the described central area of such formation with respect to central area.
In the invention described above, the bottom of the slot part of described central area can formed the curved shape of depression with the continuous central authorities in the bottom of the slot part of described two petiolareas, depth dimensions by the described central area of such formation is big, and the depth dimensions of described two petiolareas is little with respect to described central area simultaneously.
In the invention described above, the bottom of the slot part of described central area can be formed in the direction with the length direction quadrature of described slot part lower than the bottom of the slot part of described two petiolareas, little by the depth dimensions of described two petiolareas of such formation with respect to described central area.
Among the present invention, can set light spot shape and diffraction efficiency the condition of hope for, can improve the degree of freedom and the optics multiplying power of aperture with diffraction element.For example, to use diffraction element of the present invention produces when being used for optical disc apparatus with element as 3 light beams, form the main beam of 0 light composition and the beamlet that diffraction light is formed according to the lasing light emitter emitting laser, then the depth dimensions of the slot part of diffraction element from the upper surface of both sides convex strip portions that this slot part is clipped in the middle to the bottom of this slot part changes because of the position, so when the diffraction element with by preceding comparison, the peak shape of 0 light becomes the shape that the peak pin improves the share that partly is subjected to diffraction (for example central area reduce share).Therefore, 0 luminous energy that incides object lens is obtained the effect identical with strengthening NA, thereby when making main beam converge on the track of optical recording, can make spot diameter little.So, can carry out record to optical recording with low-power, can seek to save power, and be convenient to tackle heating.Owing to but the duty factor former state to diffraction element kept 50: 50, can suppress to produce the high order diffraction light again, and can amplify spot diameter the beamlet that converges on the optical recording track.Therefore, the positional precision tolerance of track and beamlet is widened, and improves operating efficiency in the time of can seeking to make CD.Even the optical recording that the track spacing is different also can suitably be obtained tracking error signal.
Description of drawings
Fig. 1 be pattern the key diagram of composition of the optical disc apparatus key component of embodiment of the present invention 1 is shown.
Fig. 2 (a) and (b), (c) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 1, cut-open view and stereographic map when the slot part length direction dissects diffraction element.
Fig. 3 is the key diagram that the light intensity distributions variation of 0 light that penetrates the diffraction element front and back of using in the embodiment of the present invention 1 is shown.
Fig. 4 (a) and (b) are respectively the key diagram of using the situation that forms hot spot in the optical disc apparatus of the present invention on optical recording to be shown and the key diagram that forms the situation of hot spot in the existing optical disc apparatus on optical recording is shown.
Fig. 5 (a) and (b), (c) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 2, cut-open view and stereographic map when the slot part length direction dissects diffraction element.
Fig. 6 (a) and (b), (c) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 3, cut-open view and stereographic map when the slot part length direction dissects diffraction element.
Fig. 7 (a) and (b), (c), (d) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 4, the cut-open view when the slot part length direction dissects diffraction element, cut-open view and the stereographic map when dissecing diffraction element with the direction of slot part length direction quadrature.
Label declaration
The 1st, optical disc apparatus, the 2nd, lasing light emitter, the 3rd, photodetector, the 10th, optical recording, the 20th, optical system, the 8th, diffraction element, the 81st, slot part, the 82nd, convex strip portions, the 810th, the bottom of slot part, the 82nd, the upper surface of convex strip portions.
Embodiment
Embodiment 1
(main assembly)
Fig. 1 be pattern the key diagram of composition of the optical disc apparatus key component of embodiment of the present invention 1 is shown.
Among Fig. 1, the optical disc apparatus 1 of present embodiment has and sends for example semiconductor laser 2 and the photodetector 3 of the laser beam of wavelength 650nm.Optical disc apparatus 1 has the optical system 40 that beam splitter 41, collimation lens 42, debugging mirror 43 and object lens 44 are set from semiconductor laser 1 toward optical recording 10.Constitute the light path of going to that semiconductor laser 2 emitting lasers is directed to optical recording 10 by these optical elements.Optical system 40 also is provided with sensor leads 45 between beam splitter 41 and photodetector 3, and constitutes the light path of returning that the return light may of optical recording 10 reflections is directed to photodetector 3 by object lens 44, debugging mirror 43, collimation lens 42, beam splitter 41 and sensor leads 45.From photodetector 3, in the behind of beam splitter 41, configuration detection goes out from semiconductor laser 2 toward optical recording the preceding monitor 5 (monitor and use photodetector) of the light that is reflected by beam splitter 41 10 the laser.
The return light may that photodetector 3 is used to detect optical recording 10 reflections produces focus error signal and tracking error signal, and these focus error signals and tracking error signal is fed back to objective lens device 7 with when the recorded information or when carrying out information regeneration.
Optical recording 10 is DVD-RAM (digital multi-purpose CD random access memory) etc. for example.Among the DVD-RAM, though not shown, will alternately form concentric circles with face and groove between the line of fluctuation, and face between line and groove all will be used as the track that forms the hole.Here, will be used to import clock from the signal that fluctuation obtains.
In the optical disc apparatus 1 of present embodiment, between semiconductor laser 2 and beam splitter 41, have main beam that the beamlet formed according to semiconductor laser 2 emitting laser outgoing-1 time diffraction light, 0 light form and+diffraction element 8 that optical grating element that beamlet that 1 light is formed is used or holographic element are formed.Therefore, can converge on the track of optical recording 10 by the main beam that object lens 44 are formed 0 light, and can be by detecting the reproduction that its return light may is carried out information with photodetector 3.Can also converge on the track of optical recording 10 by the main beam that object lens 44 are formed 0 light, carry out the information record.And then, the beamlet that the beamlet that makes-1 time light is formed by object lens 44 and+1 light are formed converges to the position that the hot spot of main beam is clipped in the middle in the track tangential direction of optical recording 10, and can utilize acquisition tracking error signals such as DPP method by detecting its return light may with photodetector 3.
(composition of diffraction element 8)
Fig. 2 (a) and (b), (c) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 1, cut-open view and stereographic map when the slot part length direction dissects diffraction element.
Shown in Fig. 2 (a) and (b), (c), in the optical disc apparatus 1 of present embodiment, arbitrary slot part 81 of diffraction element 8, the upper surface 820 of the convex strip portions 82 of the both sides that it is clipped in the middle slot part 81 all change because of the position to the depth dimensions d of the bottom 810 of slot part 81.In the present embodiment, depth dimensions d in arbitrary slot part 81 all the length direction (No.1 L represents with arrow) at slot part 81 change with step-wise manner.That is, in arbitrary slot part 81, the central area 86 of length direction is compared with its two petiolarea 87,88, and one-level is all hanged down in the bottom 810 of slot part 81, and the upper surface 820 high one-levels of convex strip portions 82, thereby the depth dimensions d of this central area 86 is big.Therefore, in the central area 86, ± 1 diffraction efficiency height.Otherwise, in two petiolareas 87,88 of the length direction of slot part 81, compare with central area 86, the bottom 810 high one-levels of slot part 81, and the upper surface 820 low one-levels of convex strip portions 82, thus the depth dimensions d of this two petiolarea 87,88 is little.So in two petiolareas 87,88, ± 1 time diffraction efficiency is low.But the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 2 (b)) is in position highly identical on the length direction, and the center of the depth direction of slot part 81 is in position highly identical between the adjacent slot part 81.Here, diffraction element 8 is in arbitrary district, and the width dimensions of slot part 81 equates all that with the aperture size of convex strip portions 82 the grating duty factor is 50: 50.
Like this in the diffraction element 8 of Zu Chenging, slot part 81 dark central areas 86 form band shape in the direction with the length direction quadrature, and semiconductor laser 2 emitting lasers incide diffraction element 8 in the mode of crossing over two shallow petiolareas 87,88 of the dark central area 86 of slot part 81 and slot part 81.Here, the far field pattern of semiconductor laser 2 emitting lasers is oval, its long axis direction corresponding to the direction of the length direction quadrature of slot part 81, short-axis direction is corresponding to the length direction of slot part 81.Fig. 2 (a) of semiconductor element 2 emitting lasers is used to converge to optical recording 10 with the zone that circle LL represents.
(effect of present embodiment and effect)
Fig. 3 is the key diagram that the light intensity distributions variation of 0 light that penetrates the diffraction element front and back of using in the embodiment of the present invention 1 is shown, Fig. 3 (a) illustrates the vertical view of diffraction element 8, the light intensity distributions of the incident light of this diffraction element 8 is shown at Fig. 3 (b), (c) simultaneously, make its direction corresponding to the diffraction element 8 shown in Fig. 3 (a), the light intensity distributions of the emergent light of this diffraction element 8 also is shown at Fig. 3 (d), (e), makes it also corresponding to the direction of the diffraction element 8 shown in Fig. 3 (a).Fig. 4 (a) and (b) are respectively the key diagram of using the situation that forms hot spot in the optical disc apparatus of the present invention on optical recording to be shown and the key diagram that forms the situation of hot spot in the existing optical disc apparatus on optical recording is shown.
Shown in Fig. 3 (a) and (b), (d), in the optical disc apparatus 1 of present embodiment, the light quantity distribution of laser beam with the direction cutting diffraction element of slot part 81 quadratures of diffraction element 8 time before and after penetrating diffraction element, it does not had big the variation; In contrast, shown in Fig. 3 (a), (c), (e), the light quantity of laser beam on the direction cutting diffraction element parallel with the slot part 81 of diffraction element 8 penetrated diffraction element 8 front and back at it change greatly.Promptly, in the diffraction element 8, the central area 86 of the length direction of slot part 81 ± 1 diffraction efficiency height, and two petiolareas 87,88 ± 1 time diffraction efficiency is low, so the light intensity of 0 light of central area 86 outgoing reduces in a large number, and the light intensity of 0 light of two petiolareas, 87,88 outgoing only reduces a little.Therefore, the peak shape of 0 light becomes the shape that the share that light quantity reduces in a large number in the central area is improved in the foot section, peak shown in the No.1 B of arrow of Fig. 3 (e).So, 0 luminous energy that incides object lens 44 is obtained the effect identical with strengthening NA.
Therefore, when making main beam converge to optical recording 10, illustrate respectively as Fig. 4 (a) and Fig. 4 (b) and to use situation of the present invention and the existing example,, can make its spot diameter little the main beam that converges to optical recording 10 according to the manner.So noise spectra of semiconductor lasers 2 emitting lasers even power is low, also can carry out record to optical recording, thereby can seek to save power and reduce cost, and be convenient to tackle heating.
In the present embodiment,, can be 50: 50 entirely, so can suppress to produce the high order diffraction light for the grating duty factor of diffraction element 8 again.Therefore, when making beamlet converge to optical recording 10, the manner is compared with existing example, and right+1 second son hot spot and-1 second son hot spot all amplify spot diameter.So the positional precision tolerance of track and beamlet is widened, improve operating efficiency in the time of seeking to make optical disc apparatus 1.And the optical recording 10 that the track spacing is different also can suitably obtain tracking error signal.
Moreover, in the present embodiment, the center that the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 2 (b)) is in the depth direction of position highly identical on the length direction and slot part 81 is in position highly identical between the adjacent slot portion, thereby has the advantage that does not produce astigmatism.
Embodiment 2
Fig. 5 (a) and (b), (c) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 2, cut-open view and stereographic map when the slot part length direction dissects diffraction element.The basic composition of the embodiment 2,3,4 that the following describes is identical with embodiment 1, thereby the identical label of identical part mark describes.
Shown in Fig. 5 (a) and (b), (c), in the optical disc apparatus 1 of the manner, also identical with embodiment 1, arbitrary slot part 81 of diffraction element 8, the upper surface 820 of the convex strip portions 82 of the both sides that it is clipped in the middle slot part 82 all change because of the position to the depth dimensions d of the bottom 810 of slot part 81.
But identical with embodiment 1 in the present embodiment, in arbitrary slot part 81, depth dimensions all changes continuously at the length direction (No.1 L represents with arrow) of slot part 81.That is, in arbitrary slot part 81, bottom 810 all is formed on the curved shape of length direction concavity, and in arbitrary convex strip portions 82, upper surface 820 all is formed on the curved shape that length direction central authorities bloat.Therefore, in arbitrary slot part 81, the central area 86 of length direction is compared with its two petiolarea 87,88, and the bottom 810 of slot part 81 is low, and upper surface 820 height of convex strip portions 82, and the depth dimensions d of this central area 86 is big.So, in the central area 86, ± 1 diffraction efficiency height.Otherwise, in two petiolareas 87,88 of the length direction of slot part 81, compare with central area 86, bottom 810 height of slot part 81, and also the upper surface 820 of convex strip portions 82 is low, thus the depth dimensions d of this two petiolarea 87,88 is little.So in two petiolareas 87,88, ± 1 time diffraction efficiency is low.But the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 5 (b)) is in position highly identical on the length direction, and the center of the depth direction of slot part 81 is in position highly identical between the adjacent slot part 81.Here, diffraction element 8 is in arbitrary district, and the width dimensions of slot part 81 equates all that with the aperture size of convex strip portions 82 the grating duty factor is 50: 50.
Like this in the diffraction element 8 of Zu Chenging, the dark central area 86 of slot part 81 and slot part 81 two shallow petiolareas 87,88 do not have clear and definite boundary line, but central area 86 forms continuous band shape in the direction with the length direction quadrature, and semiconductor laser 2 emitting lasers incide diffraction element 8 in the mode of crossing over two shallow petiolareas 87,88 of the dark central area 86 of slot part 81 and slot part 81.Here, the far field pattern of semiconductor laser 2 emitting lasers is oval, its long axis direction corresponding to the direction of the length direction quadrature of slot part 81, short-axis direction is corresponding to the length direction of slot part 81.The zone of representing with circle LL among Fig. 5 (a) of semiconductor element 2 emitting lasers is used to converge to optical recording 10.
Like this in the optical disc apparatus 1 of Zu Chenging, also as in the enforcement mode 1 with reference to Fig. 3 explanation, in the diffraction element 8, the central area 86 of the length direction of slot part 81 ± 1 diffraction efficiency height, and two petiolareas 87,88 ± 1 time diffraction efficiency is low, so the light intensity of 0 light of central area 86 outgoing reduces in a large number, and the light intensity of 0 light of two petiolareas, 87,88 outgoing only reduces a little.Therefore, the peak shape of 0 light becomes the shape that the share that light quantity reduces in a large number in the central area is improved in the foot section, peak, thereby 0 luminous energy that incides object lens 44 is obtained the effect identical with strengthening NA.So, when making main beam converge to optical recording 10, as illustrating with reference to Fig. 4 (a) in the enforcement mode 1, can make its spot diameter little to the main beam that converges to optical recording 10.So noise spectra of semiconductor lasers 2 emitting lasers even power is low, also can carry out record to optical recording, thereby can seek to save power and reduce cost, and be convenient to tackle heating.
In the present embodiment,, can be 50: 50 entirely, so can suppress to produce the high order diffraction light for the grating duty factor of diffraction element 8 again.Therefore, when making beamlet converge to optical recording 10, the manner is compared with existing example, and right+1 second son hot spot and-1 second son hot spot all amplify spot diameter.So the positional precision tolerance of track and beamlet is widened, improve operating efficiency in the time of seeking to make optical disc apparatus 1.And the optical recording 10 that the track spacing is different also can suitably obtain tracking error signal.
Moreover, in the present embodiment, the center that the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 5 (b)) is in the depth direction of position highly identical on the length direction and slot part 81 is in position highly identical between the adjacent slot portion, thereby has the advantage that does not produce astigmatism.
Embodiment 3
Fig. 6 (a) and (b), (c) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 3, cut-open view and stereographic map when the slot part length direction dissects diffraction element.
Shown in Fig. 6 (a) and (b), (c), in the optical disc apparatus 1 of the manner, also identical with embodiment 1, arbitrary slot part 81 of diffraction element 8, the upper surface 820 of the convex strip portions 82 of the both sides that it is clipped in the middle slot part 82 all change because of the position to the depth dimensions d of the bottom 810 of slot part 81.That is, in arbitrary slot part 81, bottom 810 all is formed on the curved shape of the concavity of length direction, and in arbitrary convex strip portions 82, upper surface 820 is the plane.Therefore, in arbitrary slot part 81, the central area 86 of length direction is compared with its two petiolarea 87,88, and the bottom 810 of slot part 81 is low, and the depth dimensions of this central area 86 is big.So, in the central area 86, ± 1 diffraction efficiency height.Otherwise, in two petiolareas 87,88 of the length direction of slot part 81, compare with central area 86, bottom 810 height of slot part 81, and also the upper surface 820 of convex strip portions 82 is low, thus the depth dimensions d of this two petiolarea 87,88 is little.So in two petiolareas 87,88, ± 1 time diffraction efficiency is low.Diffraction element 8 is identical with embodiment 1,2, and in arbitrary district, the width dimensions of slot part 81 equates all that with the width dimensions of convex strip portions 82 the grating duty factor is 50: 50.
But different with embodiment 1,2 in the present embodiment, the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 6 (b)) changes in the longitudinal direction.In the manner, the center of the depth direction of slot part 81 is in central area 86 depressions.
Like this in the diffraction element 8 of Zu Chenging, the dark central area 86 of slot part 81 and slot part 81 two shallow petiolareas 87,88 do not have clear and definite boundary line, but central area 86 forms continuous band shape in the direction with the length direction quadrature, and semiconductor laser 2 emitting lasers incide diffraction element 8 in the mode of crossing over two shallow petiolareas 87,88 of the dark central area 86 of slot part 81 and slot part 81.Here, the far field pattern of semiconductor laser 2 emitting lasers is oval, its long axis direction corresponding to the direction of the length direction quadrature of slot part 81, short-axis direction is corresponding to the length direction of slot part 81.The zone of representing with circle LL among Fig. 6 (a) of semiconductor element 2 emitting lasers is used to converge to optical recording 10.
In the optical disc apparatus 1 of Zu Chenging, the peak shape of 0 light also becomes the shape that the share that light quantity reduces in a large number in the central area is improved in the foot section, peak like this, thereby can make its spot diameter little to the main beam that converges to optical recording 10.So, noise spectra of semiconductor lasers 2 emitting lasers, obtaining that power is low also can be to effects such as optical recording 10 write down.Again, for the grating duty factor of diffraction element 8, can be 50: 50 entirely, thus can suppress to produce the high order diffraction light, and right+1 second son hot spot all amplifies spot diameter with-1 second son hot spot.Therefore, the positional precision tolerance of track and beamlet is widened, and improves operating efficiency in the time of seeking to make optical disc apparatus 1.
Moreover, in the manner, the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 6 (b)) is in position highly identical between the adjacent slot part 81, but changes the astigmatism that other optical system of using in this mode adaptive optical disc apparatus 1 causes on the length direction of slot part 81.Therefore, according to the manner, can absorb the astigmatism that the optical system that is used for optical disc apparatus 1 causes.
Embodiment 4
Fig. 7 (a) and (b), (c), (d) are respectively the vertical views of the diffraction element that uses in the embodiment of the present invention 4, the cut-open view when the slot part length direction dissects diffraction element, cut-open view and stereographic map when dissecing diffraction element with the direction of the length direction quadrature of slot part.
Shown in Fig. 7 (a) and (b), (d), in the optical disc apparatus 1 of the manner, the bottom 810 of the slot part 81 of diffraction element 8 and the upper surface 820 of convex strip portions 82 are the plane, and the length direction of slot part 81 (No.1 L represents with arrow) is no matter upward the upper surface 820 of the convex strip portions 82 of the both sides that slot part 81 is clipped in the middle is to the depth dimensions d position of slot part 810, Zong fixing.
Wherein, present embodiment with the direction of the length direction quadrature of slot part 81 on, the upper surface 820 of adjacent convex shaped part 82 is in highly identical position, but shown in Fig. 7 (a), (c), (d), the bottom 810 of slot part 81, its central area 83 to two petiolareas 84,85 with the direction of the length direction quadrature of slot part 81 are low.Therefore, the upper surface 820 of the convex strip portions 82 of the both sides that slot part 81 is clipped in the middle of arbitrary slot part 81 of diffraction element 8 changes because of the position to the depth dimensions d of the bottom 810 of slot part 81.So, in the dark central area 83 of slot part, ± 1 diffraction efficiency height, 84,85 ± 1 time diffraction efficiency of two petiolareas that slot part 81 is shallow is low.And identical with embodiment 1,2,3, the width dimensions of slot part 81 equates that with the width dimensions of convex strip portions 82 the grating duty factor is 50: 50 in arbitrary district of diffraction element 8.
In the present embodiment, different with embodiment 3, slot part 81 is fixing in the center (representing with dot-and-dash line C among Fig. 7 (b)) of depth direction, but with the direction of the length direction quadrature of slot part 81 on central area 83 to two petiolareas 84,85 cave in.
Like this in the diffraction element 8 of Zu Chenging, the dark central area 83 of slot part 81 and slot part 81 two shallow petiolareas 84,85 do not have clear and definite boundary line, but central area 83 forms continuous band shape in the direction with the length direction quadrature, and semiconductor laser 2 emitting lasers incide diffraction element 8 in the mode of crossing over two shallow petiolareas 84,85 of the dark central area 83 of slot part 81 and slot part 81.Here, the far field pattern of semiconductor laser 2 emitting lasers is oval, its long axis direction corresponding to the direction of the length direction quadrature of slot part 81, short-axis direction is corresponding to the length direction of slot part 81.The zone of representing with circle LL among Fig. 7 (a) of semiconductor element 2 emitting lasers is used to converge to optical recording 10.
Like this in the optical disc apparatus 1 of Zu Chenging, because the light intensity of 0 light of central area 83 outgoing reduces in a large number, and the light intensity of 0 light of two petiolareas, 84,85 outgoing only reduces a little, and the peak shape of 0 light becomes the shape that the share that light quantity reduces in a large number in the central area is improved in the foot section, peak.Therefore, can make its spot diameter little to the main beam that converges to optical recording 10, so noise spectra of semiconductor lasers 2 emitting lasers, obtaining that power is low also can be to effects such as optical recording 10 write down.Again, for the grating duty factor of diffraction element 8, can be 50: 50 entirely, thus can suppress to produce the high order diffraction light, and right+1 second son hot spot all amplifies spot diameter with-1 second son hot spot.Therefore, the positional precision tolerance of track and beamlet is widened, and improves operating efficiency in the time of seeking to make optical disc apparatus 1.
Moreover, in the present embodiment, the center of the depth direction of slot part 81 (representing with dot-and-dash line C among Fig. 7 (b)) is in position highly identical between the adjacent slot part 81, but on the length direction of slot part 81, change the astigmatism that other optical system of using in this mode adaptive optical disc apparatus 1 causes.Therefore, according to the manner, can absorb the astigmatism that the optical system that is used for optical disc apparatus 1 causes.
In addition, during astigmatism that other optical system of not considering to use in the optical disc apparatus 1 causes, also can constitute and set slot part 81 for highly identical in the longitudinal direction position in the center of depth direction, and be in position also highly identical between the slot part 81.
Claims (17)
1, a kind of diffraction element is alternately arranged many slot parts and convex strip portions, it is characterized in that,
Depth dimensions from the upper surface of both sides convex strip portions that described slot part is clipped in the middle to the bottom of this slot part is because of the position changes.
2, the diffraction element described in claim 1 is characterized in that,
Described depth dimensions changes with step-wise manner at the length direction of described slot part.
3, the diffraction element described in claim 1 is characterized in that,
Described depth dimensions changes continuously at the length direction of described slot part.
4, the diffraction element described in claim 1 is characterized in that,
Described depth dimensions is different between described many slot parts.
5, as each described diffraction element in the claim 1 to 4, it is characterized in that,
The center of the depth direction of described slot part is in the identical position of length direction height of this slot part.
6, as each described diffraction element in the claim 1 to 3, it is characterized in that,
The center of the depth direction of described slot part is in the length direction variation of this slot part.
7, as each described diffraction element in the claim 1 to 4, it is characterized in that,
The center of the depth direction of described slot part is in position highly identical between each slot part.
8, as each described diffraction element in the claim 1 to 4, it is characterized in that,
The center of the depth direction of described slot part, different between each slot part.
9, the diffraction element described in claim 1 is characterized in that,
Described slot part and the convex strip portions of alternately arranging many, form respectively and have the central area big and described depth dimensions two petiolareas, and will set for across described central area and described two petiolareas from the incidence zone of the laser of semiconductor laser less than described central area from the upper surface of described convex strip portions to the depth dimensions of the bottom of described slot part.
10, the diffraction element described in claim 9 is characterized in that,
Respectively to described slot part and the convex strip portions of alternately arranging many, the width dimensions that forms described slot part equates and the duty factor of grating is 50: 50.
11, the diffraction element described in claim 10 is characterized in that,
The bottom of the slot part of described central area is formed the bottom that is lower than described two petiolareas and the upper surface of the described convex strip portions of described central area is formed the upper surface of the described convex strip portions that is higher than described two petiolareas, little by the depth dimensions depth dimensions big, described two petiolareas simultaneously of the described central area of such formation with respect to central area.
12, the diffraction element described in claim 10 is characterized in that,
The bottom of the slot part of described central area is forming the curved shape of depression with the continuous central authorities in the bottom of the slot part of described two petiolareas, little with respect to described central area by the depth dimensions depth dimensions big, described two petiolareas simultaneously of the described central area of such formation.
13, the diffraction element described in claim 10 is characterized in that,
The bottom of the slot part of described central area is formed in the direction with the length direction quadrature of described slot part lower than the bottom of the slot part of described two petiolareas, little by the depth dimensions of described two petiolareas of such formation with respect to described central area.
14, a kind of optical disc apparatus is characterized in that,
Possess each described diffraction element in the claim 1 to 4, and
Have lasing light emitter, photodetector, formation described lasing light emitter emitting laser be directed to going to light path and the return light may of described optical recording reflection being directed to the optical system of returning light path of photodetector of optical recording,
Described optical system produces described diffraction element and use element as 3 light beams, this 3 light beam produces with element in described half-way of going to light path, form the main beam of 0 light composition and 2 beamlets of diffraction light composition according to the light of described lasing light emitter outgoing.
15, the optical disc apparatus described in claim 14 is characterized in that,
Described slot part and the convex strip portions of alternately arranging many, form big central area of depth dimensions with bottom and described depth dimensions two petiolareas respectively, and described lasing light emitter emitting laser incident is become across described central area and described two petiolareas less than described central area from described convex strip portions to described slot part.
16, the optical disc apparatus described in claim 15 is characterized in that,
Alternately arrange the width dimensions that many slot part and convex strip portions form described slot part and equate described respectively, and the duty factor of grating is 50: 50 with the width dimensions of described convex strip portions.
17, the optical disc apparatus described in claim 16 is characterized in that,
The far field pattern of described lasing light emitter emitting laser is oval, and described laser incided described diffraction element, make its long axis direction corresponding to the direction of the length direction quadrature of the described slot part of described diffraction element and its minor axis length direction corresponding to described slot part.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005086981 | 2005-03-24 | ||
| JP2005086981A JP2006268979A (en) | 2005-03-24 | 2005-03-24 | Diffraction element and optical disk drive |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1838272A true CN1838272A (en) | 2006-09-27 |
Family
ID=37015630
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2006100681910A Pending CN1838272A (en) | 2005-03-24 | 2006-03-21 | Diffraction element and optical disk device |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US20060215531A1 (en) |
| JP (1) | JP2006268979A (en) |
| CN (1) | CN1838272A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5361244A (en) * | 1991-04-10 | 1994-11-01 | Hitachi, Ltd. | Optical head and information recording apparatus |
| EP1437608A4 (en) * | 2001-09-13 | 2006-07-26 | Asahi Glass Co Ltd | Diffraction device |
| WO2003041066A1 (en) * | 2001-11-09 | 2003-05-15 | Sharp Kabushiki Kaisha | Light integration unit, optical pickup device using the unit, and optical disk device |
| JP3826082B2 (en) * | 2002-08-23 | 2006-09-27 | シャープ株式会社 | Optical pickup device |
| US7538945B2 (en) * | 2005-01-07 | 2009-05-26 | Nippon Sheet Glass Company, Limited | Optical path changing module |
-
2005
- 2005-03-24 JP JP2005086981A patent/JP2006268979A/en not_active Withdrawn
-
2006
- 2006-03-21 CN CNA2006100681910A patent/CN1838272A/en active Pending
- 2006-03-23 US US11/387,698 patent/US20060215531A1/en not_active Abandoned
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| Publication number | Publication date |
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| JP2006268979A (en) | 2006-10-05 |
| US20060215531A1 (en) | 2006-09-28 |
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